I'm new about RSocket, so please bear with me.
I am able to follow a working example of Spring boot RSocket both server and client over TCP and Websocket. However, if I have got an existing client application which implemented the standardWebSocket then can I create a new server application which implements RSocket - Spring boot and let the existing client application connect to this new server without changing any client's source code.
Actually I have tried some by with following links
Spring Websocket Client (Without STOMP)
As a result, looks like the server did not receive any messages from the client. Do I miss-understand concept here?
You have missed the fact to implement an RSocket protocol in your solution. Well, essentially server is already providing and expecting that application protocol over WebSocket, but looks like your client is still STOMP, not RSocket. Try to understand with this article: https://medium.com/netifi/differences-between-grpc-and-rsocket-e736c954e60. It's not about WebSockets, but explain what is a difference between network protocol and application one.